Observation of two new N peaks in J/psi-->ppi-n and ppi+n decays

• Published in: Physical review letters 2006-08, Vol.97 (6), p.062001-062001
• Main Authors: Ablikim, M, Bai, J Z, Ban, Y, Bian, J G, Cai, X, Chang, J F, Chen, H F, Chen, H S, Chen, H X, Chen, J C, Chen, Jin, Chen, Jun, Chen, M L, Chen, Y B, Chi, S P, Chu, Y P, Cui, X Z, Dai, H L, Dai, Y S, Deng, Z Y, Dong, L Y, Du, S X, Du, Z Z, Fang, J, Fang, S S, Fu, C D, Fu, H Y, Gao, C S, Gao, Y N, Gong, M Y, Gong, W X, Gu, S D, Guo, Y N, Guo, Y Q, Guo, Z J, Harris, F A, He, K L, He, M, He, X, Heng, Y K, Hu, H M, Hu, T, Huang, G S, Huang, L, Huang, X P, Ji, X B, Jia, Q Y, Jiang, C H, Jiang, X S, Jin, D P, Jin, S, Jin, Y, Lai, Y F, Li, F, Li, G, Li, H B, Li, H H, Li, J, Li, J C, Li, Q J, Li, R B, Li, R Y, Li, S M, Li, W G, Li, X L, Li, X Q, Li, X S, Liang, Y F, Liao, H B, Liu, C X, Liu, F, Liu, Fang, Liu, H M, Liu, J B, Liu, J P, Liu, R G, Liu, Z A, Liu, Z X, Lu, F, Lu, G R, Lu, J G, Luo, C L, Luo, X L, Ma, F C, Ma, J M, Ma, L L, Ma, Q M, Ma, X Y, Mao, Z P, Mo, X H, Nie, J, Nie, Z D, Olsen, S L, Peng, H P, Qi, N D, Qian, C D, Qin, H, Qiu, J F, Ren, Z Y, Rong, G
• Format: Article
• Language: English
• ISSN: 0031-9007

The decay J/psi-->NNpi provides an effective isospin 1/2 filter for the piN system due to isospin conservation. Using 58x10(6) J/psi decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/psi-->ppi-n+c.c. events are obtained. Besides the two well-known N* peaks at around 1500 MeV/c2 and 1670 MeV/c2, there are two new, clear N* peaks in the ppi invariant mass spectrum around 1360 MeV/c2 and 2030 MeV/c2 with statistical significance of 11sigma and 13sigma, respectively. We identify these as the first direct observation of the N*(1440) peak and a long-sought missing N* peak above 2 GeV/c2 in the piN invariant mass spectrum.